Maleic anhydride is the abbreviation of maleic anhydride, also known as maleic anhydride or dehydrated malic anhydride. It is an important organic chemical raw material or fine chemical. It is mainly used to produce unsaturated polyester resin, alkyd resin, 1,4-butanediol (BDO), tetrahydrophthalic anhydride and other chemical products. Its development and application prospects are very broad. At present, in the production process of maleic anhydride with n-butane as raw material at home and abroad, most organic solvents are used as absorbents, and the organic solvents are generally diisobutyl hexahydrophthalate (DIBE) and dibutyl phthalate (DBP).

有机溶剂吸收顺酐后通过气提工段提纯顺酐，吸收剂经分离机处理之后循环使用。以正丁烷为原料顺酐产生的废水来源于三部分，即解析真空泵排出的废水、精制真空泵排出的废水和离心机轻相排出的废水，其中混合有机酸及醋成分包括丙烯酸、马来酸、富马酸、邻苯二甲酸、六氢化邻苯二甲酸二异丁酯(DIBE)或者邻苯二甲酸二丁醋(DBP) 、丙烯酸二聚体，废水pH=0.5-1.5，总有机物含量在1.0%-1.4% ，几乎不含氮、磷和无机盐类，属于高浓度化工废水。有机酸及DIBE等溶剂是增加水体COD的源头，还含有一定量的氨(胺)基化合物、杂环化合物、酚类、苯类，属生物不易降解高浓度有机废水成分，对微生物生长具有抑制作用。此类废水中间产物均对微生物有较强的抑制作用，我们常称为生物毒性，并具有很强的腐蚀性。

After the organic solvent absorbs the maleic anhydride, the maleic anhydride is purified through the gas extraction section, and the absorbent is recycled after being processed by the separator. The waste water generated from the production of maleic anhydride using n-butane as raw material comes from three parts, namely, the waste water from the analytical vacuum pump, the waste water from the refining vacuum pump, and the waste water from the light phase of the centrifuge. The mixed organic acid and vinegar components include acrylic acid, maleic acid, fumaric acid, phthalic acid, diisobutyl hexahydrophthalate (DIBE), or dibutyl phthalate (DBP), and acrylic acid dimer. The pH of the waste water is 0.5-1.5, The total organic content is 1.0% - 1.4%, almost free of nitrogen, phosphorus and inorganic salts, belonging to high concentration chemical wastewater. Solvents such as organic acids and DIBE are the sources of increasing COD in water bodies, and also contain a certain amount of ammonia (amine) compounds, heterocyclic compounds, phenols, and benzene, which are the components of organic wastewater with high concentration that are not easily degraded by organisms, and have an inhibitory effect on microbial growth. The intermediate products of this kind of wastewater have strong inhibitory effect on microorganisms, which are often called biological toxicity and have strong corrosivity.

目前的顺酐废水处理工艺一般是：顺酐工艺废水-集水井-隔油调节池-EBR反应器(铁碳微电解)-破乳反应池-气浮系统-缓冲水池-混凝沉淀池-配水池-IC反应器-一阶氧化-中间沉淀池-二阶氧化池-二级沉淀池-臭氧氧化池-生物滤池-清水池，由于其中含有较多的难降解有机物，经过现有技术进行生物降解后仍很难达到排放标准，并且造成废水处理费用高。

At present, the treatment process of maleic anhydride wastewater is generally: maleic anhydride process wastewater - water collecting well - oil separation regulating tank - EBR reactor (iron and carbon micro-electrolysis) - demulsification reaction tank - air flotation system - buffer tank - coagulation sedimentation tank - distribution tank - IC reactor - first stage oxidation - intermediate sedimentation tank - second stage oxidation tank - second stage sedimentation tank - ozone oxidation tank - biological filter - clean water tank, because it contains more refractory organics, It is still difficult to meet the discharge standard after biodegradation by the existing technology, and the waste water treatment cost is high.

现有技术中处理顺酐废水时，把顺酐废水中的马来酸异构为富马酸，然后降温结晶得到富马酸，同时降低废水中有机物含量，但是此方法仅适用于水吸收法顺酐工艺，而不适用普遍使用的有机溶剂吸收法。

When treating maleic anhydride wastewater in the existing technology, the maleic acid in the maleic anhydride wastewater is isomerized into fumaric acid, and then the fumaric acid is obtained by cooling and crystallizing, while reducing the content of organic matter in the wastewater. However, this method is only applicable to the water absorption method of maleic anhydride process, not the commonly used organic solvent absorption method.

另外，有人提出一种顺酐废水处理的新工艺，即使用碱性萃取剂回收其中的马来酸和富马酸，降低废水中的有机物，然后再去生化处理废水，但是废水中六氢化邻苯二甲酸二异丁酯(DIBE)或者邻苯二甲酸二丁醋(DBP)的可生化降解性比富马酸、马来酸等要低很多，其主要是针对废水中的有机酸性物质的回收处理，但该方法对于废水中的难降解有机物如DIBE或者DBP没有考虑，废水难降解有机物含量依然较高，亦难以进行生化处理，主要依靠其他水稀释处理达标排放。可见，顺酐废水处理工艺需要进行改进。

In addition, a new process for the treatment of maleic anhydride wastewater was proposed, that is, to use alkaline extractants to recover the maleic acid and fumaric acid in the wastewater, reduce the organic matter in the wastewater, and then go to biochemical treatment of the wastewater. However, the biodegradability of DIBE or DBP in the wastewater is much lower than that of fumaric acid and maleic acid, It is mainly aimed at the recovery and treatment of organic acid substances in wastewater, but this method does not consider the refractory organics in wastewater, such as DIBE or DBP. The content of refractory organics in wastewater is still high, and it is also difficult to carry out biochemical treatment. It mainly depends on other water dilution treatment to meet the discharge standard. It can be seen that the treatment process of maleic anhydride wastewater needs to be improved.